1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a technique which can enhance a strength and visibility of a miniaturized display device used in a mobile phone or the like.
2. Description of Related Arts
With respect to a liquid crystal display device, there has been a strong demand for making a profile size of the display device smaller while maintaining a screen at a fixed size as well as a demand for the reduction of a thickness of a liquid crystal display panel. To achieve the reduction of thickness of the liquid crystal display panel, a thickness of the liquid crystal display panel is decreased by polishing an outer side of the liquid crystal display panel after manufacturing the liquid crystal display panel.
With respect to a glass substrate which is used for forming a TFT substrate which constitutes the liquid crystal display panel and forms pixel electrodes, TFTs (thin film transistors) and the like thereon and a counter substrate which constitutes the liquid crystal display panel and forms color filters thereon, a thickness of each substrate is standardized to 0.5 mm or 0.7 mm, for example. It is difficult to obtain such standardized glass substrate from a market. Further, such an extremely thin glass substrate causes drawbacks with respect to a mechanical strength, deflection and the like during a manufacturing process thus lowering a manufacturing yield rate. As a result, a liquid crystal display panel is formed using a standardized glass substrate and, thereafter, an outer surface of the liquid crystal display panel is polished to reduce the thickness of the liquid crystal display panel.
When the thickness of the liquid crystal display panel is reduced, there arises a drawback with respect to a mechanical strength of the liquid crystal display panel. That is, when a mechanical pressure is applied to a display screen of the liquid crystal display panel, there arises a possibility that the liquid crystal display panel is broken. To prevent such a drawback, as shown in FIG. 8, in incorporating the liquid crystal display panel in a mobile phone set or the like, a front window (hereinafter, referred to as a face plate) is mounted on a screen side of the liquid crystal display panel.
To prevent an external force applied to the face plate from being applied to the liquid crystal display panel, the face plate is arranged in a spaced-apart manner from the liquid crystal display panel. However, the constitution shown in FIG. 8 gives rise to a drawback that display quality is deteriorated as described later. Japanese patent Laid-Open Hei 11-174417 (patent document 1) discloses a technique which is provided for coping with the drawback attributed to the structure shown in FIG. 8, for example.